diff --git a/phpBB/includes/db/migration/data/3_0_1.php b/phpBB/includes/db/migration/data/3_0_1.php
index a9eac6f110..8b7c6f0f7c 100644
--- a/phpBB/includes/db/migration/data/3_0_1.php
+++ b/phpBB/includes/db/migration/data/3_0_1.php
@@ -9,6 +9,11 @@
 
 class phpbb_db_migration_data_3_0_1 extends phpbb_db_migration
 {
+	public function effectively_installed()
+	{
+		return version_compare($this->config['version'], '3.0.1', '>=');
+	}
+
 	static public function depends_on()
 	{
 		return array('phpbb_db_migration_data_3_0_1_rc1');
diff --git a/phpBB/includes/db/migration/data/3_0_10.php b/phpBB/includes/db/migration/data/3_0_10.php
index 89afb8a432..b24a876bac 100644
--- a/phpBB/includes/db/migration/data/3_0_10.php
+++ b/phpBB/includes/db/migration/data/3_0_10.php
@@ -9,6 +9,11 @@
 
 class phpbb_db_migration_data_3_0_10 extends phpbb_db_migration
 {
+	public function effectively_installed()
+	{
+		return version_compare($this->config['version'], '3.0.10', '>=');
+	}
+
 	static public function depends_on()
 	{
 		return array('phpbb_db_migration_data_3_0_10_rc3');
diff --git a/phpBB/includes/db/migration/data/3_0_10_rc1.php b/phpBB/includes/db/migration/data/3_0_10_rc1.php
index ca8fadec61..46b7db4e59 100644
--- a/phpBB/includes/db/migration/data/3_0_10_rc1.php
+++ b/phpBB/includes/db/migration/data/3_0_10_rc1.php
@@ -9,6 +9,11 @@
 
 class phpbb_db_migration_data_3_0_10_rc1 extends phpbb_db_migration
 {
+	public function effectively_installed()
+	{
+		return version_compare($this->config['version'], '3.0.10-rc1', '>=');
+	}
+
 	static public function depends_on()
 	{
 		return array('phpbb_db_migration_data_3_0_9');
diff --git a/phpBB/includes/db/migration/data/3_0_10_rc2.php b/phpBB/includes/db/migration/data/3_0_10_rc2.php
index 1f39ea48e0..5e85467202 100644
--- a/phpBB/includes/db/migration/data/3_0_10_rc2.php
+++ b/phpBB/includes/db/migration/data/3_0_10_rc2.php
@@ -9,6 +9,11 @@
 
 class phpbb_db_migration_data_3_0_10_rc2 extends phpbb_db_migration
 {
+	public function effectively_installed()
+	{
+		return version_compare($this->config['version'], '3.0.10-rc2', '>=');
+	}
+
 	static public function depends_on()
 	{
 		return array('phpbb_db_migration_data_3_0_10_rc1');
diff --git a/phpBB/includes/db/migration/data/3_0_10_rc3.php b/phpBB/includes/db/migration/data/3_0_10_rc3.php
index cd82bb573e..6ff81f7776 100644
--- a/phpBB/includes/db/migration/data/3_0_10_rc3.php
+++ b/phpBB/includes/db/migration/data/3_0_10_rc3.php
@@ -9,6 +9,11 @@
 
 class phpbb_db_migration_data_3_0_10_rc3 extends phpbb_db_migration
 {
+	public function effectively_installed()
+	{
+		return version_compare($this->config['version'], '3.0.10-rc3', '>=');
+	}
+
 	static public function depends_on()
 	{
 		return array('phpbb_db_migration_data_3_0_10_rc2');
diff --git a/phpBB/includes/db/migration/data/3_0_11.php b/phpBB/includes/db/migration/data/3_0_11.php
index 9f25f0e489..1a63508593 100644
--- a/phpBB/includes/db/migration/data/3_0_11.php
+++ b/phpBB/includes/db/migration/data/3_0_11.php
@@ -9,6 +9,11 @@
 
 class phpbb_db_migration_data_3_0_11 extends phpbb_db_migration
 {
+	public function effectively_installed()
+	{
+		return version_compare($this->config['version'], '3.0.11', '>=');
+	}
+
 	static public function depends_on()
 	{
 		return array('phpbb_db_migration_data_3_0_11_rc2');
diff --git a/phpBB/includes/db/migration/data/3_0_11_rc1.php b/phpBB/includes/db/migration/data/3_0_11_rc1.php
index 43e0156760..19703bcc35 100644
--- a/phpBB/includes/db/migration/data/3_0_11_rc1.php
+++ b/phpBB/includes/db/migration/data/3_0_11_rc1.php
@@ -9,6 +9,11 @@
 
 class phpbb_db_migration_data_3_0_11_rc1 extends phpbb_db_migration
 {
+	public function effectively_installed()
+	{
+		return version_compare($this->config['version'], '3.0.11-rc1', '>=');
+	}
+
 	static public function depends_on()
 	{
 		return array('phpbb_db_migration_data_3_0_10');
diff --git a/phpBB/includes/db/migration/data/3_0_11_rc2.php b/phpBB/includes/db/migration/data/3_0_11_rc2.php
index e5bb3e44a6..219d44c4e0 100644
--- a/phpBB/includes/db/migration/data/3_0_11_rc2.php
+++ b/phpBB/includes/db/migration/data/3_0_11_rc2.php
@@ -9,6 +9,11 @@
 
 class phpbb_db_migration_data_3_0_11_rc2 extends phpbb_db_migration
 {
+	public function effectively_installed()
+	{
+		return version_compare($this->config['version'], '3.0.11-rc2', '>=');
+	}
+
 	static public function depends_on()
 	{
 		return array('phpbb_db_migration_data_3_0_11_rc1');
diff --git a/phpBB/includes/db/migration/data/3_0_12_rc1.php b/phpBB/includes/db/migration/data/3_0_12_rc1.php
index 4fe0828716..c23e8b24b8 100644
--- a/phpBB/includes/db/migration/data/3_0_12_rc1.php
+++ b/phpBB/includes/db/migration/data/3_0_12_rc1.php
@@ -11,6 +11,11 @@
 
 class phpbb_db_migration_data_3_0_12_rc1 extends phpbb_db_migration
 {
+	public function effectively_installed()
+	{
+		return version_compare($this->config['version'], '3.0.12-rc1', '>=');
+	}
+
  	static public function depends_on()
 	{
 		return array('phpbb_db_migration_data_3_0_11');
diff --git a/phpBB/includes/db/migration/data/3_0_1_rc1.php b/phpBB/includes/db/migration/data/3_0_1_rc1.php
index 9f1c04809d..2fc2849d04 100644
--- a/phpBB/includes/db/migration/data/3_0_1_rc1.php
+++ b/phpBB/includes/db/migration/data/3_0_1_rc1.php
@@ -9,6 +9,11 @@
 
 class phpbb_db_migration_data_3_0_1_rc1 extends phpbb_db_migration
 {
+	public function effectively_installed()
+	{
+		return version_compare($this->config['version'], '3.0.1-rc1', '>=');
+	}
+
 	public function update_schema()
 	{
 		return array(
diff --git a/phpBB/includes/db/migration/data/3_0_2.php b/phpBB/includes/db/migration/data/3_0_2.php
index 8661578281..8aa975f779 100644
--- a/phpBB/includes/db/migration/data/3_0_2.php
+++ b/phpBB/includes/db/migration/data/3_0_2.php
@@ -9,6 +9,11 @@
 
 class phpbb_db_migration_data_3_0_2 extends phpbb_db_migration
 {
+	public function effectively_installed()
+	{
+		return version_compare($this->config['version'], '3.0.2', '>=');
+	}
+
 	static public function depends_on()
 	{
 		return array('phpbb_db_migration_data_3_0_2_rc2');
diff --git a/phpBB/includes/db/migration/data/3_0_2_rc1.php b/phpBB/includes/db/migration/data/3_0_2_rc1.php
index 851060c3b5..6081cd682c 100644
--- a/phpBB/includes/db/migration/data/3_0_2_rc1.php
+++ b/phpBB/includes/db/migration/data/3_0_2_rc1.php
@@ -9,6 +9,11 @@
 
 class phpbb_db_migration_data_3_0_2_rc1 extends phpbb_db_migration
 {
+	public function effectively_installed()
+	{
+		return version_compare($this->config['version'], '3.0.2-rc1', '>=');
+	}
+
 	static public function depends_on()
 	{
 		return array('phpbb_db_migration_data_3_0_1');
diff --git a/phpBB/includes/db/migration/data/3_0_2_rc2.php b/phpBB/includes/db/migration/data/3_0_2_rc2.php
index c255e55aef..bb76c270d7 100644
--- a/phpBB/includes/db/migration/data/3_0_2_rc2.php
+++ b/phpBB/includes/db/migration/data/3_0_2_rc2.php
@@ -9,6 +9,11 @@
 
 class phpbb_db_migration_data_3_0_2_rc2 extends phpbb_db_migration
 {
+	public function effectively_installed()
+	{
+		return version_compare($this->config['version'], '3.0.2-rc2', '>=');
+	}
+
 	static public function depends_on()
 	{
 		return array('phpbb_db_migration_data_3_0_2_rc1');
diff --git a/phpBB/includes/db/migration/data/3_0_3.php b/phpBB/includes/db/migration/data/3_0_3.php
index 2873c798fd..82039a109b 100644
--- a/phpBB/includes/db/migration/data/3_0_3.php
+++ b/phpBB/includes/db/migration/data/3_0_3.php
@@ -9,6 +9,11 @@
 
 class phpbb_db_migration_data_3_0_3 extends phpbb_db_migration
 {
+	public function effectively_installed()
+	{
+		return version_compare($this->config['version'], '3.0.3', '>=');
+	}
+
 	static public function depends_on()
 	{
 		return array('phpbb_db_migration_data_3_0_3_rc1');
diff --git a/phpBB/includes/db/migration/data/3_0_3_rc1.php b/phpBB/includes/db/migration/data/3_0_3_rc1.php
index 49e4170c3f..5e300962b7 100644
--- a/phpBB/includes/db/migration/data/3_0_3_rc1.php
+++ b/phpBB/includes/db/migration/data/3_0_3_rc1.php
@@ -9,6 +9,11 @@
 
 class phpbb_db_migration_data_3_0_3_rc1 extends phpbb_db_migration
 {
+	public function effectively_installed()
+	{
+		return version_compare($this->config['version'], '3.0.3-rc1', '>=');
+	}
+
 	static public function depends_on()
 	{
 		return array('phpbb_db_migration_data_3_0_2');
diff --git a/phpBB/includes/db/migration/data/3_0_4.php b/phpBB/includes/db/migration/data/3_0_4.php
index 590ae3c69f..34af9fa4ae 100644
--- a/phpBB/includes/db/migration/data/3_0_4.php
+++ b/phpBB/includes/db/migration/data/3_0_4.php
@@ -9,6 +9,11 @@
 
 class phpbb_db_migration_data_3_0_4 extends phpbb_db_migration
 {
+	public function effectively_installed()
+	{
+		return version_compare($this->config['version'], '3.0.4', '>=');
+	}
+
 	static public function depends_on()
 	{
 		return array('phpbb_db_migration_data_3_0_4_rc1');
diff --git a/phpBB/includes/db/migration/data/3_0_4_rc1.php b/phpBB/includes/db/migration/data/3_0_4_rc1.php
index 8f44baf046..f63bebcf75 100644
--- a/phpBB/includes/db/migration/data/3_0_4_rc1.php
+++ b/phpBB/includes/db/migration/data/3_0_4_rc1.php
@@ -9,6 +9,11 @@
 
 class phpbb_db_migration_data_3_0_4_rc1 extends phpbb_db_migration
 {
+	public function effectively_installed()
+	{
+		return version_compare($this->config['version'], '3.0.4-rc1', '>=');
+	}
+
 	static public function depends_on()
 	{
 		return array('phpbb_db_migration_data_3_0_3');
diff --git a/phpBB/includes/db/migration/data/3_0_5.php b/phpBB/includes/db/migration/data/3_0_5.php
index 65b292207e..077ed251d2 100644
--- a/phpBB/includes/db/migration/data/3_0_5.php
+++ b/phpBB/includes/db/migration/data/3_0_5.php
@@ -9,6 +9,11 @@
 
 class phpbb_db_migration_data_3_0_5 extends phpbb_db_migration
 {
+	public function effectively_installed()
+	{
+		return version_compare($this->config['version'], '3.0.5', '>=');
+	}
+
 	static public function depends_on()
 	{
 		return array('phpbb_db_migration_data_3_0_5_rc1part2');
diff --git a/phpBB/includes/db/migration/data/3_0_5_rc1.php b/phpBB/includes/db/migration/data/3_0_5_rc1.php
index a0893a0dbb..df85ee4f7d 100644
--- a/phpBB/includes/db/migration/data/3_0_5_rc1.php
+++ b/phpBB/includes/db/migration/data/3_0_5_rc1.php
@@ -9,6 +9,11 @@
 
 class phpbb_db_migration_data_3_0_5_rc1 extends phpbb_db_migration
 {
+	public function effectively_installed()
+	{
+		return version_compare($this->config['version'], '3.0.5-rc1', '>=');
+	}
+
 	static public function depends_on()
 	{
 		return array('phpbb_db_migration_data_3_0_4');
diff --git a/phpBB/includes/db/migration/data/3_0_5_rc1part2.php b/phpBB/includes/db/migration/data/3_0_5_rc1part2.php
index 0597fc0ff8..d2fad7a7f8 100644
--- a/phpBB/includes/db/migration/data/3_0_5_rc1part2.php
+++ b/phpBB/includes/db/migration/data/3_0_5_rc1part2.php
@@ -9,6 +9,11 @@
 
 class phpbb_db_migration_data_3_0_5_rc1part2 extends phpbb_db_migration
 {
+	public function effectively_installed()
+	{
+		return version_compare($this->config['version'], '3.0.5-rc1', '>=');
+	}
+
 	static public function depends_on()
 	{
 		return array('phpbb_db_migration_data_3_0_5_rc1');
diff --git a/phpBB/includes/db/migration/data/3_0_6.php b/phpBB/includes/db/migration/data/3_0_6.php
index a7b88e510a..1b0cbb1435 100644
--- a/phpBB/includes/db/migration/data/3_0_6.php
+++ b/phpBB/includes/db/migration/data/3_0_6.php
@@ -9,6 +9,11 @@
 
 class phpbb_db_migration_data_3_0_6 extends phpbb_db_migration
 {
+	public function effectively_installed()
+	{
+		return version_compare($this->config['version'], '3.0.6', '>=');
+	}
+
 	static public function depends_on()
 	{
 		return array('phpbb_db_migration_data_3_0_6_rc4');
diff --git a/phpBB/includes/db/migration/data/3_0_6_rc1.php b/phpBB/includes/db/migration/data/3_0_6_rc1.php
index 5ebeceeed7..0f85084e65 100644
--- a/phpBB/includes/db/migration/data/3_0_6_rc1.php
+++ b/phpBB/includes/db/migration/data/3_0_6_rc1.php
@@ -9,6 +9,11 @@
 
 class phpbb_db_migration_data_3_0_6_rc1 extends phpbb_db_migration
 {
+	public function effectively_installed()
+	{
+		return version_compare($this->config['version'], '3.0.6-rc1', '>=');
+	}
+
 	static public function depends_on()
 	{
 		return array('phpbb_db_migration_data_3_0_5');
diff --git a/phpBB/includes/db/migration/data/3_0_6_rc2.php b/phpBB/includes/db/migration/data/3_0_6_rc2.php
index 7cbda4c616..a9c497b3cd 100644
--- a/phpBB/includes/db/migration/data/3_0_6_rc2.php
+++ b/phpBB/includes/db/migration/data/3_0_6_rc2.php
@@ -9,6 +9,11 @@
 
 class phpbb_db_migration_data_3_0_6_rc2 extends phpbb_db_migration
 {
+	public function effectively_installed()
+	{
+		return version_compare($this->config['version'], '3.0.6-rc2', '>=');
+	}
+
 	static public function depends_on()
 	{
 		return array('phpbb_db_migration_data_3_0_6_rc1');
diff --git a/phpBB/includes/db/migration/data/3_0_6_rc3.php b/phpBB/includes/db/migration/data/3_0_6_rc3.php
index 209057ec70..eca19fc2ff 100644
--- a/phpBB/includes/db/migration/data/3_0_6_rc3.php
+++ b/phpBB/includes/db/migration/data/3_0_6_rc3.php
@@ -9,6 +9,11 @@
 
 class phpbb_db_migration_data_3_0_6_rc3 extends phpbb_db_migration
 {
+	public function effectively_installed()
+	{
+		return version_compare($this->config['version'], '3.0.6-rc3', '>=');
+	}
+
 	static public function depends_on()
 	{
 		return array('phpbb_db_migration_data_3_0_6_rc2');
diff --git a/phpBB/includes/db/migration/data/3_0_6_rc4.php b/phpBB/includes/db/migration/data/3_0_6_rc4.php
index 62f0e91a7d..19611d3c56 100644
--- a/phpBB/includes/db/migration/data/3_0_6_rc4.php
+++ b/phpBB/includes/db/migration/data/3_0_6_rc4.php
@@ -9,6 +9,11 @@
 
 class phpbb_db_migration_data_3_0_6_rc4 extends phpbb_db_migration
 {
+	public function effectively_installed()
+	{
+		return version_compare($this->config['version'], '3.0.6-rc4', '>=');
+	}
+
 	static public function depends_on()
 	{
 		return array('phpbb_db_migration_data_3_0_6_rc3');
diff --git a/phpBB/includes/db/migration/data/3_0_7.php b/phpBB/includes/db/migration/data/3_0_7.php
index 3e215ff905..97cdf4e3f1 100644
--- a/phpBB/includes/db/migration/data/3_0_7.php
+++ b/phpBB/includes/db/migration/data/3_0_7.php
@@ -9,6 +9,11 @@
 
 class phpbb_db_migration_data_3_0_7 extends phpbb_db_migration
 {
+	public function effectively_installed()
+	{
+		return version_compare($this->config['version'], '3.0.7', '>=');
+	}
+
 	static public function depends_on()
 	{
 		return array('phpbb_db_migration_data_3_0_7_rc2');
diff --git a/phpBB/includes/db/migration/data/3_0_7_pl1.php b/phpBB/includes/db/migration/data/3_0_7_pl1.php
index ffe0836d02..176854a8a6 100644
--- a/phpBB/includes/db/migration/data/3_0_7_pl1.php
+++ b/phpBB/includes/db/migration/data/3_0_7_pl1.php
@@ -9,6 +9,11 @@
 
 class phpbb_db_migration_data_3_0_7_pl1 extends phpbb_db_migration
 {
+	public function effectively_installed()
+	{
+		return version_compare($this->config['version'], '3.0.7-pl1', '>=');
+	}
+
 	static public function depends_on()
 	{
 		return array('phpbb_db_migration_data_3_0_7');
diff --git a/phpBB/includes/db/migration/data/3_0_7_rc1.php b/phpBB/includes/db/migration/data/3_0_7_rc1.php
index b30830c21d..daf52213b9 100644
--- a/phpBB/includes/db/migration/data/3_0_7_rc1.php
+++ b/phpBB/includes/db/migration/data/3_0_7_rc1.php
@@ -9,6 +9,11 @@
 
 class phpbb_db_migration_data_3_0_7_rc1 extends phpbb_db_migration
 {
+	public function effectively_installed()
+	{
+		return version_compare($this->config['version'], '3.0.7-rc1', '>=');
+	}
+
 	static public function depends_on()
 	{
 		return array('phpbb_db_migration_data_3_0_6');
diff --git a/phpBB/includes/db/migration/data/3_0_7_rc2.php b/phpBB/includes/db/migration/data/3_0_7_rc2.php
index c2720b532f..8167d8fa40 100644
--- a/phpBB/includes/db/migration/data/3_0_7_rc2.php
+++ b/phpBB/includes/db/migration/data/3_0_7_rc2.php
@@ -9,6 +9,11 @@
 
 class phpbb_db_migration_data_3_0_7_rc2 extends phpbb_db_migration
 {
+	public function effectively_installed()
+	{
+		return version_compare($this->config['version'], '3.0.7-rc2', '>=');
+	}
+
 	static public function depends_on()
 	{
 		return array('phpbb_db_migration_data_3_0_7_rc1');
diff --git a/phpBB/includes/db/migration/data/3_0_8.php b/phpBB/includes/db/migration/data/3_0_8.php
index 8043b934b0..25baaf0f07 100644
--- a/phpBB/includes/db/migration/data/3_0_8.php
+++ b/phpBB/includes/db/migration/data/3_0_8.php
@@ -9,6 +9,11 @@
 
 class phpbb_db_migration_data_3_0_8 extends phpbb_db_migration
 {
+	public function effectively_installed()
+	{
+		return version_compare($this->config['version'], '3.0.8', '>=');
+	}
+
 	static public function depends_on()
 	{
 		return array('phpbb_db_migration_data_3_0_8_rc1');
diff --git a/phpBB/includes/db/migration/data/3_0_8_rc1.php b/phpBB/includes/db/migration/data/3_0_8_rc1.php
index 8214f44f17..13e68a7953 100644
--- a/phpBB/includes/db/migration/data/3_0_8_rc1.php
+++ b/phpBB/includes/db/migration/data/3_0_8_rc1.php
@@ -9,6 +9,11 @@
 
 class phpbb_db_migration_data_3_0_8_rc1 extends phpbb_db_migration
 {
+	public function effectively_installed()
+	{
+		return version_compare($this->config['version'], '3.0.8-rc1', '>=');
+	}
+
 	static public function depends_on()
 	{
 		return array('phpbb_db_migration_data_3_0_7_pl1');
diff --git a/phpBB/includes/db/migration/data/3_0_9.php b/phpBB/includes/db/migration/data/3_0_9.php
index c562f1f2cf..b35350dbb5 100644
--- a/phpBB/includes/db/migration/data/3_0_9.php
+++ b/phpBB/includes/db/migration/data/3_0_9.php
@@ -9,6 +9,11 @@
 
 class phpbb_db_migration_data_3_0_9 extends phpbb_db_migration
 {
+	public function effectively_installed()
+	{
+		return version_compare($this->config['version'], '3.0.9', '>=');
+	}
+
 	static public function depends_on()
 	{
 		return array('phpbb_db_migration_data_3_0_9_rc4');
diff --git a/phpBB/includes/db/migration/data/3_0_9_rc1.php b/phpBB/includes/db/migration/data/3_0_9_rc1.php
index 367bb25734..be6ced2566 100644
--- a/phpBB/includes/db/migration/data/3_0_9_rc1.php
+++ b/phpBB/includes/db/migration/data/3_0_9_rc1.php
@@ -9,6 +9,11 @@
 
 class phpbb_db_migration_data_3_0_9_rc1 extends phpbb_db_migration
 {
+	public function effectively_installed()
+	{
+		return version_compare($this->config['version'], '3.0.9-rc1', '>=');
+	}
+
 	static public function depends_on()
 	{
 		return array('phpbb_db_migration_data_3_0_8');
diff --git a/phpBB/includes/db/migration/data/3_0_9_rc2.php b/phpBB/includes/db/migration/data/3_0_9_rc2.php
index c8566d54a5..0bec42a8de 100644
--- a/phpBB/includes/db/migration/data/3_0_9_rc2.php
+++ b/phpBB/includes/db/migration/data/3_0_9_rc2.php
@@ -9,6 +9,11 @@
 
 class phpbb_db_migration_data_3_0_9_rc2 extends phpbb_db_migration
 {
+	public function effectively_installed()
+	{
+		return version_compare($this->config['version'], '3.0.9-rc2', '>=');
+	}
+
 	static public function depends_on()
 	{
 		return array('phpbb_db_migration_data_3_0_9_rc1');
diff --git a/phpBB/includes/db/migration/data/3_0_9_rc3.php b/phpBB/includes/db/migration/data/3_0_9_rc3.php
index da977e9666..a339670932 100644
--- a/phpBB/includes/db/migration/data/3_0_9_rc3.php
+++ b/phpBB/includes/db/migration/data/3_0_9_rc3.php
@@ -9,6 +9,11 @@
 
 class phpbb_db_migration_data_3_0_9_rc3 extends phpbb_db_migration
 {
+	public function effectively_installed()
+	{
+		return version_compare($this->config['version'], '3.0.9-rc3', '>=');
+	}
+
 	static public function depends_on()
 	{
 		return array('phpbb_db_migration_data_3_0_9_rc2');
diff --git a/phpBB/includes/db/migration/data/3_0_9_rc4.php b/phpBB/includes/db/migration/data/3_0_9_rc4.php
index 0bfe26985c..ab5c302611 100644
--- a/phpBB/includes/db/migration/data/3_0_9_rc4.php
+++ b/phpBB/includes/db/migration/data/3_0_9_rc4.php
@@ -9,6 +9,11 @@
 
 class phpbb_db_migration_data_3_0_9_rc4 extends phpbb_db_migration
 {
+	public function effectively_installed()
+	{
+		return version_compare($this->config['version'], '3.0.9-rc4', '>=');
+	}
+
 	static public function depends_on()
 	{
 		return array('phpbb_db_migration_data_3_0_9_rc3');
diff --git a/phpBB/includes/db/migration/data/3_1_0_dev.php b/phpBB/includes/db/migration/data/3_1_0_dev.php
index 14953591d1..ac8882cb3a 100644
--- a/phpBB/includes/db/migration/data/3_1_0_dev.php
+++ b/phpBB/includes/db/migration/data/3_1_0_dev.php
@@ -9,6 +9,11 @@
 
 class phpbb_db_migration_data_3_1_0_dev extends phpbb_db_migration
 {
+	public function effectively_installed()
+	{
+		return version_compare($this->config['version'], '3.1.0-dev', '>=');
+	}
+
 	static public function depends_on()
 	{
 		return array(
diff --git a/phpBB/includes/db/migration/data/extensions.php b/phpBB/includes/db/migration/data/extensions.php
index ff54d0d933..f077741883 100644
--- a/phpBB/includes/db/migration/data/extensions.php
+++ b/phpBB/includes/db/migration/data/extensions.php
@@ -9,6 +9,11 @@
 
 class phpbb_db_migration_data_extensions extends phpbb_db_migration
 {
+	public function effectively_installed()
+	{
+		return $this->db_tools->sql_table_exists($this->table_prefix . 'ext');
+	}
+
 	static public function depends_on()
 	{
 		return array('phpbb_db_migration_data_3_0_11');
diff --git a/phpBB/includes/db/migration/data/style_update_p1.php b/phpBB/includes/db/migration/data/style_update_p1.php
index 701afc0d78..7506b7c49b 100644
--- a/phpBB/includes/db/migration/data/style_update_p1.php
+++ b/phpBB/includes/db/migration/data/style_update_p1.php
@@ -9,6 +9,11 @@
 
 class phpbb_db_migration_data_style_update_p1 extends phpbb_db_migration
 {
+	public function effectively_installed()
+	{
+		return !$this->db_tools->sql_table_exists($this->table_prefix . 'styles_imageset');
+	}
+
 	static public function depends_on()
 	{
 		return array('phpbb_db_migration_data_3_0_11');
diff --git a/phpBB/includes/db/migration/data/style_update_p2.php b/phpBB/includes/db/migration/data/style_update_p2.php
index 1a8cc9da58..ef13f45d9b 100644
--- a/phpBB/includes/db/migration/data/style_update_p2.php
+++ b/phpBB/includes/db/migration/data/style_update_p2.php
@@ -9,6 +9,11 @@
 
 class phpbb_db_migration_data_style_update_p2 extends phpbb_db_migration
 {
+	public function effectively_installed()
+	{
+		return !$this->db_tools->sql_table_exists($this->table_prefix . 'styles_imageset');
+	}
+
 	static public function depends_on()
 	{
 		return array('phpbb_db_migration_data_style_update_p1');
diff --git a/phpBB/includes/db/migration/data/timezone.php b/phpBB/includes/db/migration/data/timezone.php
index 3658120629..66085b8872 100644
--- a/phpBB/includes/db/migration/data/timezone.php
+++ b/phpBB/includes/db/migration/data/timezone.php
@@ -9,6 +9,11 @@
 
 class phpbb_db_migration_data_timezone extends phpbb_db_migration
 {
+	public function effectively_installed()
+	{
+		return !$this->db_tools->sql_column_exists($this->table_prefix . 'users', 'user_dst');
+	}
+
 	static public function depends_on()
 	{
 		return array('phpbb_db_migration_data_3_0_11');
diff --git a/phpBB/includes/db/migration/data/timezone_p2.php b/phpBB/includes/db/migration/data/timezone_p2.php
index 15f1a3e414..38347a0c63 100644
--- a/phpBB/includes/db/migration/data/timezone_p2.php
+++ b/phpBB/includes/db/migration/data/timezone_p2.php
@@ -9,6 +9,11 @@
 
 class phpbb_db_migration_data_timezone_p2 extends phpbb_db_migration
 {
+	public function effectively_installed()
+	{
+		return !$this->db_tools->sql_column_exists($this->table_prefix . 'users', 'user_dst');
+	}
+
 	static public function depends_on()
 	{
 		return array('phpbb_db_migration_data_timezone');
diff --git a/phpBB/includes/db/migration/install.php b/phpBB/includes/db/migration/install.php
deleted file mode 100644
index 95f3a3b994..0000000000
--- a/phpBB/includes/db/migration/install.php
+++ /dev/null
@@ -1,138 +0,0 @@
-<?php
-/**
-*
-* @package migration
-* @copyright (c) 2012 phpBB Group
-* @license http://opensource.org/licenses/gpl-license.php GNU Public License v2
-*
-*/
-
-class phpbb_db_migration_install
-{
-	/**
-	* List of phpBB versions/what migration identifier
-	* 	contains the updates that should have been installed already
-	*
-	* @var array
-	*/
-	protected $version_to_migration = array(
-		'3.0.1-rc1'		=> 'phpbb_db_migration_data_3_0_1_rc1',
-		'3.0.1'	   		=> 'phpbb_db_migration_data_3_0_1',
-		'3.0.2-rc1'		=> 'phpbb_db_migration_data_3_0_2_rc1',
-		'3.0.2-rc2'		=> 'phpbb_db_migration_data_3_0_2_rc2',
-		'3.0.2'	   		=> 'phpbb_db_migration_data_3_0_2',
-		'3.0.3-rc1'		=> 'phpbb_db_migration_data_3_0_3_rc1',
-		'3.0.3'	   		=> 'phpbb_db_migration_data_3_0_3',
-		'3.0.4-rc1'		=> 'phpbb_db_migration_data_3_0_4_rc1',
-		'3.0.4'	   		=> 'phpbb_db_migration_data_3_0_4',
-		'3.0.5-rc1'		=> array(
-			'phpbb_db_migration_data_3_0_5_rc1',
-			'phpbb_db_migration_data_3_0_5_rc1part2',
-		),
-		'3.0.5'	   		=> 'phpbb_db_migration_data_3_0_5',
-		'3.0.6-rc1'		=> 'phpbb_db_migration_data_3_0_6_rc1',
-		'3.0.6-rc2'		=> 'phpbb_db_migration_data_3_0_6_rc2',
-		'3.0.6-rc3'		=> 'phpbb_db_migration_data_3_0_6_rc3',
-		'3.0.6-rc4'		=> 'phpbb_db_migration_data_3_0_6_rc4',
-		'3.0.6'	   		=> 'phpbb_db_migration_data_3_0_6',
-		'3.0.7-rc1'		=> 'phpbb_db_migration_data_3_0_7_rc1',
-		'3.0.7-rc2'		=> 'phpbb_db_migration_data_3_0_7_rc2',
-		'3.0.7'	   		=> 'phpbb_db_migration_data_3_0_7',
-		'3.0.7-pl1'		=> 'phpbb_db_migration_data_3_0_7_pl1',
-		'3.0.8-rc1'		=> 'phpbb_db_migration_data_3_0_8_rc1',
-		'3.0.8'			=> 'phpbb_db_migration_data_3_0_8',
-		'3.0.9-rc1'     => 'phpbb_db_migration_data_3_0_9_rc1',
-		'3.0.9-rc2'     => 'phpbb_db_migration_data_3_0_9_rc2',
-		'3.0.9-rc3'     => 'phpbb_db_migration_data_3_0_9_rc3',
-		'3.0.9-rc4'     => 'phpbb_db_migration_data_3_0_9_rc4',
-		'3.0.9'			=> 'phpbb_db_migration_data_3_0_9',
-		'3.0.10-rc1'    => 'phpbb_db_migration_data_3_0_10_rc1',
-		'3.0.10-rc2'    => 'phpbb_db_migration_data_3_0_10_rc2',
-		'3.0.10-rc3'    => 'phpbb_db_migration_data_3_0_10_rc3',
-		'3.0.10'		=> 'phpbb_db_migration_data_3_0_10',
-		'3.0.11-rc1'	=> 'phpbb_db_migration_data_3_0_11_rc1',
-		'3.0.11-rc2'	=> 'phpbb_db_migration_data_3_0_11_rc2',
-		'3.0.11'		=> 'phpbb_db_migration_data_3_0_11',
-		'3.0.12-rc1'	=> 'phpbb_db_migration_data_3_0_12_rc1',
-		'3.1.0-dev'		=> array(
-			'phpbb_db_migration_data_style_update_p1',
-			'phpbb_db_migration_data_style_update_p2',
-			'phpbb_db_migration_data_timezone',
-			'phpbb_db_migration_data_timezone_p2',
-			'phpbb_db_migration_data_extensions',
-			'phpbb_db_migration_data_3_1_0_dev',
-		),
-	);
-
-	public function install(phpbb_db_driver $db, phpbb_db_tools $db_tools, $table_prefix, $version)
-	{
-		$this->create_table($db_tools, $table_prefix);
-
-		$this->guess_installed_migrations($db, $table_prefix, $version);
-	}
-
-	protected function create_table(phpbb_db_tools $db_tools, $table_prefix)
-	{
-		if (!$db_tools->sql_table_exists($table_prefix . 'migrations'))
-		{
-			$db_tools->sql_create_table($table_prefix . 'migrations', array(
-				'COLUMNS'		=> array(
-					'migration_name'			=> array('VCHAR', ''),
-					'migration_depends_on'		=> array('TEXT', ''),
-					'migration_schema_done'		=> array('BOOL', 0),
-					'migration_data_done'		=> array('BOOL', 0),
-					'migration_data_state'		=> array('TEXT', ''),
-					'migration_start_time'		=> array('TIMESTAMP', 0),
-					'migration_end_time'		=> array('TIMESTAMP', 0),
-				),
-				'PRIMARY_KEY'	=> 'migration_name',
-			));
-		}
-	}
-
-	/**
-	* Guess what migrations have been installed based on phpBB version
-	*
-	* @param mixed $version
-	*/
-	protected function guess_installed_migrations(phpbb_db_driver $db, $table_prefix, $version)
-	{
-		$installed = array();
-		foreach ($this->version_to_migration as $compare => $migration_list)
-		{
-			if (version_compare($version, $compare, '>='))
-			{
-				// The migration should have effectively been installed already
-				if (!is_array($migration_list))
-				{
-					$migration_list = array($migration_list);
-				}
-
-				foreach ($migration_list as $migration_name)
-				{
-					$sql = 'SELECT 1 FROM ' . $table_prefix . "migrations
-						WHERE migration_name = '" . $db->sql_escape($migration_name) . "'";
-					$result = $db->sql_query($sql);
-					$row = $db->sql_fetchrow($result);
-					$db->sql_freeresult($result);
-
-					if (!$row)
-					{
-						$sql_ary = array(
-							'migration_name'			=> $migration_name,
-							'migration_depends_on'		=> serialize($migration_name::depends_on()),
-							'migration_schema_done'		=> 1,
-							'migration_data_done'		=> 1,
-							'migration_data_state'		=> '',
-							'migration_start_time'		=> 0,
-							'migration_end_time'		=> 0,
-						);
-						$sql = 'INSERT INTO ' . $table_prefix . 'migrations ' .
-							$db->sql_build_array('INSERT', $sql_ary);
-						$db->sql_query($sql);
-					}
-				}
-			}
-		}
-	}
-}
diff --git a/phpBB/install/database_update.php b/phpBB/install/database_update.php
index f220a1f684..459839f393 100644
--- a/phpBB/install/database_update.php
+++ b/phpBB/install/database_update.php
@@ -193,13 +193,22 @@ header('Content-type: text/html; charset=UTF-8');
 
 // End startup code
 
-// Make sure migrations have been installed. If not, install migrations and guess what migrations have been installed
+// Make sure migrations have been installed.
 $db_tools = $phpbb_container->get('dbal.tools');
 if (!$db_tools->sql_table_exists($table_prefix . 'migrations'))
 {
-	$migrations_installer = new phpbb_db_migration_install();
-	$migrations_installer->install($db, $db_tools, $table_prefix, $config['version']);
-	unset($migrations_installer);
+	$db_tools->sql_create_table($table_prefix . 'migrations', array(
+		'COLUMNS'		=> array(
+			'migration_name'			=> array('VCHAR', ''),
+			'migration_depends_on'		=> array('TEXT', ''),
+			'migration_schema_done'		=> array('BOOL', 0),
+			'migration_data_done'		=> array('BOOL', 0),
+			'migration_data_state'		=> array('TEXT', ''),
+			'migration_start_time'		=> array('TIMESTAMP', 0),
+			'migration_end_time'		=> array('TIMESTAMP', 0),
+		),
+		'PRIMARY_KEY'	=> 'migration_name',
+	));
 }
 
 $migrator = $phpbb_container->get('migrator');